It is important that even experienced neurophysiologists undergo some level of education or training prior to use of the probes. Our probe catalog has short descriptions of the probe process, acute and chronic assembly techniques, a multichannel amplifier schematic, the available probe designs and relevant publications describing probe fabrication and use. Using this catalog and initial consultation on the phone or through email, the experienced neurophysiologist can often be successful with basic acute experiments. An E-mail alias which goes to all of our users has been useful for allowing them to communicate with each other and broadcast problems which may have been solved by other users. Our webpage also contains information relevant to first-time and even more advanced probe users. Users who have special needs and/or difficult preparations are invited to visit our institution for one-on-one consultation. During this fourth year of the grant period, the Center held a satellite symposium at the Society for Neuroscience meeting. The symposium, titled "New Developments in Mulitchannel Recording and Stimulation," included presentations on Center-supplied probes as well as other electrode technologies. More than 150 people attended the symposium.